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    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
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    <title>丰富的样式</title>
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    <!-- <p>在文本框中点击，您会看到黄色的背景：</p>

    <form>
        First name: <input type="text" name="firstname" /><br>
        Last name: <input type="text" name="lastname" />
    </form>

    <p><b>注释：</b>如果 :focus 用于 IE8 ，则必须声明
        <!DOCTYPE>。</p> -->
    <div>
        <p>
            These are the necessary steps:
        </p>
        <ul>
            <li>Insert key</li>
            <li>Turn key <strong>clockwise</strong></li>
            <li>Push accelerator</li>
            <p>Do <em>push the brake at the same time as the accelerator</em></p>
        </ul>
    </div>

    <!-- 鼠标伪类 -->
    <a href="https://www.baidu.com/">百度</a>
    <a href="https://www.baidu.com/">百度</a>

</body>
<style>
    /* input:focus {
        background-color: yellow;
    } */
    p:first-child {
        font-weight: bold;
    }
    li:first-child {
        text-transform: uppercase;
    }
    a:link:hover:lang(de){
        color: gray;
    }
</style>

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